The present invention concernes a liquid feed apparatus for feeding liquids, for example, different kinds of fuel oils such as gasoline and light oil, and different kinds of engine oils.
There has been a liquid feed apparatus capable of feeding plural kinds of liquids only by this one apparatus, and in addition, one liquid feed nozzle and a part of a liquid feed pipe in a pump device have also been used in common to feed the plural kinds of liquids. In such a liquid feed apparatus, change-over valves are provided in the common pipe, and these change-over valves are actuated to communicate one of storage tanks of the selected kind of liquid with the common pipe by a selection signal from a liquid kind selection switch, whereby a feed channel is formed between the tank and the liquid feed pipe.
Then, the pump is normally rotated and a nozzle valve is opened to feed the desired kind of liquid from the tank containing the same through the pipe and the liquid feed nozzle to, for example, a fuel tank of a car in the case that the liquid is a fuel oil. Afterward, the liquid feed nozzle is closed and the pump is then stopped to bring the liquid feed to an end.
At the end of liquid feed, a part of a fed liquid remains in the pump and the common pipe. In consequence, when another kind of liquid is next fed, the last liquid left in the common pipe by the last liquid feed is mixed with the fed liquid at the time of the next liquid feed to inconveniently form a mixed liquid.